With development of a wireless communications network, due to openness of a wireless physical layer medium and electromagnetic signal transmission in a broadcast manner, data transmitted in the wireless communications network is more easily stolen by a third party than data transmitted in a wired network. Therefore, how to improve data transmission reliability and security in the wireless communications network is an urgent technical problem that needs to be resolved.
A conventional manner for ensuring the data transmission security in the wireless communications network may be: Data transmission security at a high layer (for example, a wireless link layer or an application layer) of a wireless communications network system is improved, for example, a cryptology theory—based data encryption method, or various security protocols. However, transmission security at a physical layer becomes a key that restricts security of the entire wireless communications network system, and how to ensure data transmission security at the physical layer becomes an important research topic.
An artificial noise (artificial noise) technology is a method that is applied to a multiple-antenna system and that is for improving the data transmission security at the physical layer. Specifically, a wanted signal is transmitted on a primary channel for data transmission, to ensure that an authorized receiver normally receives the wanted signal. In addition, an unwanted signal that is set artificially is transmitted in a direction orthogonal to the primary channel, to interfere with an unauthorized receiver in another direction as much as possible, and improve the data transmission security at the physical layer.
However, currently, artificial noise technology research mainly focuses on a single-cell scenario. When the artificial noise technology is applied to a multi-cell scenario of a cellular wireless communications network, a transmitted artificial noise not only interferes with an unauthorized receiver, but also causes interference to another authorized receiver with a same frequency as an authorized receiver. In this way, another user is affected, and performance of the cellular wireless communications network deteriorates.